The present invention relates generally to the field of machine tools, and more particularly, to the field of automated machining centers utilizing multiple tools that simultaneously operate on one or more workpieces.
Machine tools have been in use for centuries. Rotary filing machines date at least to the eighteenth century with milling machines appearing a short time thereafter. Automation began in the early twentieth century, and by the late twentieth century computers were commonly utilized to control automation. Presently, it is common for a numerically controlled automated machine tool to operate with multiple tools functioning at the same time on one or more workpieces.
For instance, in a manufacturing process where milling of a workpiece is necessary, the workpiece is typically held on a table and the machine utilizes one, two, three, four, or more spindles each securing a tool. The spindles may be connected to one another and move together in parallel motion. The table may move in the x-y plane and the spindles of the machine along the z axis. The table may also move in the x-y plane as well as along another axis or multiple other axes and/or the spindles may also move in the x-y plane. Thus, it is possible to machine a 2-D or 3-D workpiece along multiple axes.
As refinement of the computer driven automation of machine tools has advanced, so has the ability to adapt machines for multiple tools. Rather than having multiple machines wherein the spindles of a particular machine each hold only one tool, spindles may be made adaptable to multiple tools. For some time, tools in a spindle were required to be manually changed, for instance, if a tool became damaged or required sharpening/adjustment or if a different tool was desired. With advances in computerized automation, a machine may contain a magazine of tools wherein the spindle is adapted to cooperate with the magazine and automatically change tools as programmed. Magazines are typically located near the spindle, contain multiple tools, and are rotatable such that as it rotates a tool can be removed from the spindle and a different tool placed in the spindle. Spindles may be moved between use and loading positions.
Because a spindle may be adaptable to many different sizes and types of tools, the size of the magazines can vary. When magazines are large in order to contain a large number of tools, they gain flexibility in being able to perform many different functions with individual spindles acting in a single machine tool. A magazine may be supplied with tools allowing the spindle to drill, cut, grind, mill, punch, etch, etc., by rotating the magazine to a different position. However, by adding tools to a magazine and thereby increasing magazine size, efficiency of the operation on the workpiece may suffer because large magazines require spindles to be separated by a greater distance. In other words, spacing between spindles is directly impacted by magazine size. Spacing can become an important factor with respect to waste material from a workpiece. For example, four spindles may operate on a flat workpiece, with each spindle cutting a portion of the workpiece. Because of the minimum spacing required between spindles, voids are present between spindles in which the workpiece cannot be worked on, resulting in waste product.
Thus, there exists a need for a machining center that permits a wide range of tools to be utilized by each spindle while permitting multiple spindles to function at a relatively close distance to one another, thereby reducing waste.